diff -r 34bf9f389749 -r 49580ca85ab7 thermferm/mqtt.c
--- a/thermferm/mqtt.c	Fri Aug 18 17:45:14 2017 +0200
+++ b/thermferm/mqtt.c	Sat Jul 14 17:21:25 2018 +0200
@@ -1,5 +1,5 @@
 /*****************************************************************************
- * Copyright (C) 2016-2017
+ * Copyright (C) 2016-2018
  *   
  * Michiel Broek <mbroek at mbse dot eu>
  *
@@ -419,7 +419,11 @@
 
 
 
-void publishDBirth(void)
+/**
+ * @brief Publish DBIRTH for all active units. If there are no active units, don't
+ *        publish anything. This function should be called at program start.
+ */
+void publishDBirthAll(void)
 {
     char	*payload = NULL;
     units_list	*unit;
@@ -428,13 +432,17 @@
     payload = payload_header();
     payload = xstrcat(payload, (char *)"{\"units\":[");
     for (unit = Config.units; unit; unit = unit->next) {
-	if (comma)
-	    payload = xstrcat(payload, (char *)",");
-	payload = xstrcat(payload, unit_data(unit, true));
-	comma = TRUE;
+	if (unit->mode != UNITMODE_OFF) {
+	    if (comma)
+	    	payload = xstrcat(payload, (char *)",");
+	    payload = xstrcat(payload, unit_data(unit, true));
+	    comma = TRUE;
+	}
     }
-    payload = xstrcat(payload, (char *)"]}}");
-    publisher(mosq, topic_base((char *)"DBIRTH"), payload, true);
+    if (comma) {	// Only publish if there is at least one unit active.
+    	payload = xstrcat(payload, (char *)"]}}");
+    	publisher(mosq, topic_base((char *)"DBIRTH"), payload, true);
+    }
     free(payload);
     payload = NULL;
 }
@@ -465,6 +473,53 @@
 
 
 
+void publishDBirth(units_list *unit)
+{
+#ifdef HAVE_MOSQUITTO_H
+
+    char        *payload = NULL, *topic = NULL;
+
+    if (mqtt_use) {
+	payload = payload_header();
+	payload = xstrcat(payload, unit_data(unit, true));
+	payload = xstrcat(payload, (char *)"}");
+	topic = xstrcat(topic_base((char *)"DBIRTH"), (char *)"/");
+	topic = xstrcat(topic, unit->alias);
+	publisher(mosq, topic, payload, true);
+	free(payload);
+	payload = NULL;
+	free(topic);
+	topic = NULL;
+    }
+#endif
+}
+
+
+
+void publishDDeath(units_list *unit)
+{
+#ifdef HAVE_MOSQUITTO_H
+
+    char        *topic = NULL;
+
+    if (mqtt_use) {
+	// First delete presistent DBIRTH topic
+	topic = xstrcat(topic_base((char *)"DBIRTH"), (char *)"/");
+	topic = xstrcat(topic, unit->alias);
+	publisher(mosq, topic, NULL, true);
+	free(topic);
+	topic = NULL;
+	topic = xstrcat(topic_base((char *)"DDEATH"), (char *)"/");
+	topic = xstrcat(topic, unit->alias);
+	publisher(mosq, topic, NULL, true);
+	free(topic);
+	topic = NULL;
+    }
+#endif
+}
+
+
+
 void publishNData(bool birth, int flag)
 {
 #ifdef HAVE_MOSQUITTO_H
@@ -550,15 +605,6 @@
 
 
 
-void publishBirth(void)
-{
-    publishNData(true, 0);
-    publishDBirth();
-}
-
-
-
-
 void mqtt_connect(void)
 {
 #ifdef HAVE_MOSQUITTO_H
@@ -630,7 +676,8 @@
          * Initialise is complete, report our presence state
          */
         mosquitto_loop_start(mosq);
-	publishBirth();
+	publishNData(true, 0);
+	publishDBirthAll();
     }
 #endif
 }
@@ -648,8 +695,8 @@
 	 * After that, remove the retained topic.
          */
         syslog(LOG_NOTICE, "MQTT disconnecting");
-	publisher(mosq, topic_base((char *)"DBIRTH"), NULL, true);
 	publisher(mosq, topic_base((char *)"NBIRTH"), NULL, true);
+	publisher(mosq, topic_base((char *)"NDEATH"), NULL, true);
         mqtt_last_mid = mqtt_mid_sent;
         mqtt_status = STATUS_WAITING;
 	mqtt_my_shutdown = TRUE;